Method of coating containers



Oct. 11, 1938. H. T. SCOTT 2,133,213

METHOD OF COATING CONTAINERS Filed Oct. 16, 1934 5 Sheets-Sheet 1 Oct. 11,- 1938.

H. T. SCOTT METHOD OF COATING CONTAINERS Filed Oct. 16;, 1954 5 Sheets-Sheet 2 Oct. 11, 1938. I H. T. SCOTT 2,133,213

METHOD OF COATING CONTAINERS Filed Oct. 16, 1954 5 Sheets-Sheet 3 Oct. 11,- 1938.

H. T. SCOTT METHOD OF COATING CONTAINERS Filed Oct. 16, 1934 5 Sheets-Sheet 4 H. T. SCOTT Oct. 11, 1938.

METHOD OF COATING CONTAINERS 5 Sheets-Sheet 5 Filed Oct. 16, 1934' Patented Oct. 11, 1938 PATENT OFFICE METHOD or COATING commas Henry T. Scott, Toledo, Ohio, assignor to The American Paper Bottle Company, Toledo, Ohio, a corporation of Ohio.

Application October 16, 1934, Serial No. 748,563

4 Claims.

This invention relates to methods of coating containers and particularly to methods of applying coatings to paper containers primarily intended for the packaging and dispensing of liq- 'uids.

In Patent No. 2,047,891, issued July 14, 1936, is disclosed a paper container which, while well adapted to serve as an envelope for commodities of various kinds, is particularly suitable for the packaging of liquids. It is fabricated of relatively stiff paper and is in the form of a tube of rectangular cross section with its upper and lower ends sealed. Where liquids are to be charged into the container prior to sealing it is essential that the container in its entirety be given a coating of some substance which will render the same liquid proof so that no leakage may subsequently occur. The coating material which I may employ may vary considerably, or in accordance with the characteristics of the materials which are to be packaged. Where food products are to be packaged, particularly milk or milk products, it is highly desirable that the liquid proofing coating substance should be of such character as to remain neutral in the presence of the liquid contents of the package while at-the same time performing its function of preventing contact with the paper of the liquid contents of the container, thereby preventing softening of the walls of the container and also occupying any minute openings in the paper itself or between the joints of the container and thereby preventing direct leak-' age.

The method which comprises the subject matter of the present invention may be carried out in a mechanism designed especially to receive from a container fabricating machine a container of the type shown in my patent above referred to, to move this container through a bath of molten paraflin to drain the excess paraflin therefrom after issuing from the bath, and finally to eject the container from the parafiining apparatus and to position the same so as to be readily engageable by a conveyor mechanism for transporting to other apparatus for charging, closing and sealing. The container as it comes to the paraflining unit has its bottom closed and top open. It is introduced into the bath of paraflln bottom end foremost so that the molten parailin has access to the interior of the container only after the open end of the container has been moved below the surface of the parafiln bath. As the container fills with paraflin the air which is contained therein is displaced by the paramn, the incoming stream of paraflin running immediately to the bottom of the container and the level of the liquid rising rapidly from the bottom toward the open top thereof thus insuring that all contained air is expelled. After the container has been completely submerged it is carried through the paraflin bath in such manner that all of its surfaces are thoroughly exposed to the paraffin, the'container not being positively held by any of the carrying mechanism but being so transported in a carrier that it may have limited movements relatively to the carrier in all directions and may freely respond, to a limited extent, to the surging movements of the paraflin bath brought about by the operation of the mechanism. Each individual paper fibre of the container, both upon the outer and inner surfaces thereof is so exposed to the coating substance that the container as it issues from the bath is completely and thoroughly coated with the impregnating substance.

While the improved method is particularly useful when employed in the treatment of paper containers of square cross-section, it will be obvious to one skilled in the art that it may likewise be used in the coating of paper containers which vary widely in shape and size. Likewise it will be appreciated that the method may be practiced by the aid of mechanisms which differ substantially in design and specific mode of operation. In the accompanying drawings one form of such mechanism is illustrated, by means of which the method may be conveniently practiced, and this mechanism will be described in detail. It is, however, as will be understood, but one of a number of mechanisms which may be employed for this purpose.

In thedrawings:

Figure l is a view of the coating apparatus taken from the side, many of the parts being shown in section and others having been removed for the purpose of more fully disclosing interior details;

Figure 2 is a view of the apparatus as it would be seen from the right (Figure 1) certain of the operating parts being shown in elevation and certain parts being broken away to show the underlying elements;

Figure 3 is a view of the apparatus as from'the left (Figure l) certain of the parts being shown in section and others partially broken away;

Figure 4 is a side elevation, partly broken away, of a container receiving unit which forms part of the apparatus;

Figure 5 is a section on line 55 of Figure 1; Figure 6 is a section on line 66 of Figure 1; Figure 7 is a section on line 1-1 of Figure 3;

Figure 8 is a section on line 33 of Figure 6; and

Figure 9 is a perspective view of one of the container carriers.

The apparatus is designed for the rapid handling of a continuous series of paper containers, receiving successive containers presented to it, passing these containers through the paraflin bath and effecting the discharge thereof. It is primarily intended to form portion of a rapidly operating automatic machine in which blanks are rapidly detached from a pack, erected into tubular form, closed at one end, coated, charged, closed and sealed. It may of course be made to have any desired capacity and rate of operation.

The casing or housing in which the bath of paraflin is enclosed and which also houses the operating parts of the coating mechanism is indicated at It, the lower portion of this housing being especially designed for the retention of a substantial body of molten paraflln while the upper portion may be of lighter construction. A removable bottom plate is indicated at H and this plate may be taken oil? whenever it is desired to clean the apparatus. The normal paraffin level is indicated by the letter L and it will be understood that additional quantities of paraifin will be introduced from time to time to replace that which passes out in the shape of surface coatings upon the containers which pass through the apparatus. A conveyor chain is indicated at |2 this chain being endless and is supported upon three sprockets |3,- l4 and I5 one of which as for instance the sprocket 5, may be intermittently driven by any suitable mechanism. A guide It serves to support the conveyor chain at one point where it changes the direction of its travel. Mounted upon certain of the individual links of this chain are con tainer carrying elements l8 and there are a relatively large number of these elements, only a few being illustrated. Carriers l8 are closely spaced and the chain is so driven that each carrier is advanced from its container receiving position, indicated at B in Figure 1 to its container discharging Position indicated at D by a series of step by step movements. One of the carriers is shown in perspective in Figure 9 and it is shown in this figure at the angle which it makes with the horizontal when the conveyor chain link to which it is secured is moving in a vertical path. It comprises essentially a five sided box like member with somewhat greater interior dimensions than the exterior dimensions of the container, indicated at C in chain lines, which it is to house and to transport through the bath. Any suitable means may be utilized for securing the rear wall of the container to a chain link and the rear wall of the carrier, which faces the: open side, is also provided with a series of apertures I! through which paraflin may enter the carrier and which 7 also permit the introduction of ejecting rods for effecting the discharge of the container, in a manner to be hereinafter more fully described.

The other two larger walls of the carrier, indicated at 20 and 2|, are imperforate and the wall 20 is also curved or made concave, as shown, while the wall 2| is preferably flat. The end walls of the carrier have apertures 22 formed therein to permit the free entry and escape ,of

liquid paraflin. That end of the carrier which is lowermost at the time that the container to be coated is introduced therein, is provided with an inner central transversely extending rib 23 which injury from such contact.

The carriers shown to the right (Figure 1) descend in the operation of the device and are empty. As each carrier reaches the position of the carrier indicated at B the motion of the conveyor chain is temporarily halted and a container is introduced into the same to occupy the position shown in Figure 9. The means for introducing the container will now be described.

A container receiving chute is indicated generally at S this chute being vertically disposed to receive containers successively dropped into the same by mechanism which is not illustrated. The chute includes oppositely facing stationary guide plates and oppositely facing swinging guide plates 3|. Plates 3| are secured at their lower ends to the upstanding side members 32 of a U-shaped frame generally indicated at 33. Frame 33 has integral therewith a laterally extending cylindrical bearing member 34 which is rotatably supported upon a cylindrical stud 35 mounted in the end of a supporting frame member 36. The frame therefore, together with the plates 3|, may swing or oscillate about the axis of stud 35 from the postion in which it is shown in Figure 4 to the position in which it is shown in Figure 5. Assuming that a container is dropped into the chute with open end lowermost, as indicated at C in Figure 4, the swinging motion of the movable portion of the chute, includ the plates 3| and frame 33 effects the movement of the container to the position indicated at C in Figure 5,

the closed bottom of the container then being lowermost and the container occupying a position inclined to the horizontal.

To effect this swinging movement the frame is connected to a drive shaft 31, the teeth of a segment 33 integral with sleeve 34 meshing with the teeth of a second segment 39 pivotally mounted upon a stud 40 and segment 39 being integral with an arm 4| which is connected by means of a link 42 with the upper end of a lever 43, lever 43 being pivoted to the frame at 44 and carrying a roller 45 which lies within a camway formed within a cam 46 mounted upon shaft 31. Rotation of cam 46 therefore results in oscillation of the frame from its upper vertically disposed position to its lower inclined position in timed relation to the other operating parts of the mechanism.

The movements of the container positioning frame just described are coordinated with the movements of the conveyor chain and, when a container has been removed to the position indicated at C in Figure 5, it is in register with the carrier B within the housing l0, and also in register with an aperture formed in the wall of the housing. It is therefore in a position to be moved laterally inwardly of the housing and into the mouth of carrier B which is positioned to receive it. The means for effecting this inward movement includes the pusher 40 slidably mounted upon the frame for horizontal movement, the pusher 40 having the same inclination to the horizontal as have the apertures formed in the housing and also the carrier B. For effecting sliding movement of the pusher it is connected to an intermittently oscillating lever 4| by means of link 42, lever 43, and link-44, the lever '43 being mounted upon a fixed pivot 45.

The means for oscillating lever 4| is not illus- 2,133,213 tratedbut it will be understood that any suitable t means may be employed to operatively connect this lever'to shaft 31 .and to produce oscillations 1 of this'lev'e'rat properly timed intervals. ,Im-

'- mediately after'o'scillating tothrust a container C laterally'into "the carrier B the pusher is re:

3 tracted and the frame 33 and blades 3| are swung,

theleft (Figure 1) andfinallyu --to vertical positionto'receive a. following container; 'The conveyor chain isactuate'd andas 'the carrier just changed moves downwardly an unloaded carrier co'ming' into-register "with the container charging opening form' ed in the housing wall and ready to receive 'next'fol lowing" container. The carrier B within which a container has just been placed will 'beln'caved downwardly into the paraffin bath,thence'horizontally tiiward re t e occupiesthe position Dt I As may-be seen from an'inspe'cti n offFigure 1 one'of the bottom edges-oi the-ebntaine'rp first reaches the level of thf upper {surface o f "the parafiinarid-the'bottom of thecbntainjei' is lowermost during the'time 'that'the'conta'inr is, actually un'dergoingthe process ofi inersion so that any air originally withinthe" anl'e'is displaced by molten paraflint fiowilig upwardly and making its escape {from thefparailin bath.

Eventually'the' carrier turns around the axis'pf sprocket l3 and assumes 'a"lioriz'ontalposition. In' this movement the open side f the; carrier'is turned'downwardly and when thelcarrier has reached a completely horizontal position as "indicated at B ,;is facing directly downwardly,'the container either resting'against" that wall of the carrier which has heretofore been designated the rear wall, and'whi'ch' 'is connected to the ass'o ciated chain link; or resting againstfthe curved guide plate 41 andbein'g moved along this'plate by the action of the'carrier; Y A

- When the carrier reaches the position indicated at B the container which" i't carries isa'bout to emerge from the paraffin bath with its closed bottom uppermost so that the paramn twill 'drain rapidly from its interior. Eventually,, and after a further series'of step bystep movements of the conveyor, the carrier with itsjcoated cont mer eaches the" position D (Figure 1)) and may then be ejected from the housing. For the purpose of bringing about thisejection an ejecting mechanism is provided 'which'includes a plurality of parallel ejecting fingers 50 supported at their rear ends upona-vertically disposed plate' the lower end of which is slidably supported upon guide rods, one of which is indicated"at 5 2,v'

Each finger so 'is in alignmentfjwi th fall aper-f ture formed in a perforated guide'plate 53 and also in alignment with tlie periorations '19 formed end of oscillating'leverll previously referred to 1 and will be reciprocated "forwardly and rearwardly when level" 4| isactuated. When re-.

'tions in guide plate 53 andthrough theregister? ing'perforations I9 in the rear wall'of theLc'arrierj in the rearfwall or 'carrier'D when" that carrier has reached thediscl'1;arge position shown in Fig ure 1." Slide '5 lie operatively connected by'ineans' of a; link 54, lever 55 and link 56' withjtlie upper ciprocated forwardly or to thefleftKFigure the fingers 50 after passing'through the perfora- D will contact with the inner "wall of the container C housed within the carrierandwill thrust this container outwardly through ari aperture formed in the housing" to permit its'p'a'ssa e and intoa rocking frame 60 which at'that instant is positioned to receive' it. The rocking frame lifl' includes a member'Bl one end of which is pro vided with-two .hubs and '65 I rotatably mounted upon a supporting stud so that this frame member mayhave swinging movement about the axisof stud 54. M

' Frame-member =65 a 616 Keyed to stud lilsoas to be rotatable therewit ,"hubrGS lying inter mediate hubs 56 616i 'f ,8 l'ne?mem-- berli v j A spring pressed-detent 6!lc airriec'l by hub 66 ;,norma, lly has its; outer end projecting, within 65,: respe t v having inturned .to -,insure-' retention; of the conntirety swings As will e, f e 1 p ep a (laminar just 'd s' fiare df flrin the housing willt'occupyt the position (1 itsfppen-end;} being -lowermost. It

will be understood 0f .c0ll1-Ste -thal; as. the con 'tainer ejected. from the housing, the receivinglrame described. isin, register with the aperture formed a in the housing. Y A rotatory 'ni'over'ri'ent is then transmit qd -t0 the-stud 164 by mechanism, which is Iillustrated in :Fi'gulte 3 and is seen:to includeasegment]l fixed onstud 64, the Zteethffof this segment; meshing with t the teeth of a $gment12 pivotally'supported at "l3 upen aframe member. Oscillation-1of segment T2 isfefiectedby means of link-M; the lowerend of. which is connected to a lever: 15 carrying a roller 16 which is in engagement-with a cam 11 mounted onshaftii l.v t

Two" cushioning springs 1 adapted ,to- :be engag'ed' by. one or the; other oftabutment '19; respectively,' on linkflfi dampen shocks'incidental to the operation of the mechanism .just de-' scribed, the adjacent-ends of these springs hear ing against'ai'commoncentral spring-abutment an; e V I "By reason bf .tn fact that his, hubs: i me Q members 5| are notpositively connected to the oscillating driving studsjlbut are only releasably connected v to'.thisstucl through the inter-- mediary of the detent .61, it :is not possible for breakage, to occur shouldlfortinstanee a container come. to rest after having been only partially introduced into the rocking {frame andbetween the: container 'supporting blades TIL-portion of the cgntainerfor instance still overlying the edge of the discharge ape'rtureformed in the housing. Should thefrocking wframeflncludin'g members 6 l and 6,5, start downwardly ,with a. container "in such zp ositionas thisfl theaopposition' to the movement e1 frame member 6[anditsassociat'ed blades- 10 offered by the container will be sufficiently great'to cause the'detent 61' to be cammed into .its receivingrecess andout of recess 68, thus permitting rotation of, hub 66 and frame member '65 .ifelativelytto shubs 62 -and*63 and-frame member 5|. jI'he operator"perceiving the .separation of thetwo elements of the-transfer frame will stop the machine and remove the-jammed container whereupon; the frame member 6 I" may be again swung to its normal relative" position with respect to: framermember 65',- the det'e'nt 61 again gentering" recess 68 land releasably locking the hubs together. :2

After a containerdischarged'froin the'hou'sillg in anormal -manner"has.,-been*.lowered"tothe position in which it has beenindicatedat C in arms' 'lli andamoved forwardlyinto aposition to Figure 6 it is tobe'removed ,from-betweenl the be engaged by a conveyor. This movement from between arms 10 is effected by means of an extractor 82 which comprises an angular member the lower horizontal end of which is secured to a reciprocable member 83 and the vertical portion of which lies parallel to the housing wall and, in its rearmost position, lies within a recess formed within the housing wall. Member 83 is guided in its reciprocating movements by means of parallel guides one of which is indicated at 84 and to the under side of this member is secured a rack 85 the teeth of which mesh with the teeth of a gear 86 fixed upon a shaft 81. Shaft 81 is rotatably supported in a bearing 88 and carries at its outer end a pinion 89 the teeth of this pinion meshing with the teeth of a rack 90 slidably supported for longitudinal movements and carrying a roller 9| which lies within a camway formed in the revoluble cam 92 also fixed on shaft 31. Revolution of cam 92 therefore results in reciprocating movement of slide 83 and hence causes the extractor finger to move outwardly between blades 10 at the proper time and to remove a container which may be standing between these blades.

As mentioned previously the container will then pass on to a suitable conveyor which is not illustrated. The transfer frame including frame members BI and 65 is enclosed save for a container outlet port formed in the forward wall thereof and within this housing is located a heating unit, in this case including the conduit 93 for a heating medium such as steam as it is desired to maintain the paraflin upon the container walls in liquid condition at this point. Also mounted upon this housing is a steam chamber 94 for maintaining the interior temperature of the housing at the proper point.

The various mechanisms described are of course actuated in a desired timed relationship, a container to be coated being inserted into an empty carrier at the same time that a coated container is being ejected from the housing.

I find it to be preferable, in fabricating containers to be subsequently coated with a coating substance such as parafiin, to utilize a paper which is porous in order that the parafiin may penetrate into the intersticesthereof. Hard papers can be rendered liquid proof only with great difficulty and the coating is often nonuniform over the surface of the article made therefrom. To insure that the paper used has the necessary mechanical strength and stiffness, and at the same time the necessary porosity, a somewhat thicker sheet is used than'would be necessary were the paper harder. A paper of the solid bleached sulphite type having a weight of approximately .028 pound per .001 inch thickness per square yard has been found to be satisfactory. Kraft paper may also be used and also combinations of kraft and sulphite papers. In any event paper of the desired porosity will have a considerable nap comprising projecting fibers or filaments and it is desired that all of these projecting fibers be thoroughly coated during the coating operation.

As the container enters the parafiln bath, the moisture and air between the fibers of the paper is expelled by the action of the paraffin. It is essential that the spaces left vacant by the exclusion of moisture and air be filled with coating material so that a continuous leakproof coating is provided. As the container enters the parafiin .bath, its lowermost side wall is first presented to the liquid parafiin in such a position that the air and moisture in the pores of the paper may pass freely upward. Following this the then uppermost side wall will be so presented and immersed. The bottom also is disposed at such angle that the discharge of moisture and air therefrom is facilitated. As the container progresses further into the paraffin bath, to the horizontal position, the sides of the container which were previously vertical become horizontal and the air and moisture locked in the pores of the paper may escape more easily from these sides. Further movement of the container through the paraflin bath is accompanied by rotation thereof so that the two remaining sides are in an approximately horizontal position facilitating the escape of the air and moisture. The movement of the container through the bath is such that the container is rolled within the bath to present the several sides of the container successively to the horizontal or at least causes them to assume substantial angles to the vertical. This is desirable inasmuch as the moisture content of the paper, as well as the minute quantities of air caught in the interstices of the fibers, are more readily dislodged from horizontally disposed paper surfaces than from vertically disposed paper surfaces. Thus particles of moisture and air expelled from the lower portion of a vertically disposed paper sheet will tend to re-attach themselves as they move upwardly or downwardly as the case may be, along the surfaces of the sheet. When the sheet .is horizontally disposed, or disposed at a substantial angle to the vertical, any particles of moisture or air once discharged will rapidly separate themselves from the sheet by moving vertically upwardly or downwardly and will not have opportunity for such re-attachment. It is important therefore that the mechanism be of such character that the container as it passes through the bath causes each of the fiat sides thereof, at one time or another, to be disposed either horizontally or at a substantial angle to the vertical.

It will be appreciated that, due to the fact that the container has parallel opposing side walls, when it is disposed in a truly horizontal position, air expelled from the upper surface of the lower side wall, and some air expelled from the vertical side walls may, upon rising, be intercepted by the upper horizontally disposed side wall and trapped against the lower surface thereof. likewise water expelled from the upper side wall and vertical walls will descend and be intercepted by the lower horizontal side wall. Because of the further rolling motion imparted to the container however any such intercepted water or air is not permitted to remain upon or cover any spot upon which it is originally deposited, but will be caused to flow laterally so that at one time or another every portion of the entire area of each wall of the container is fully exposed to the bath.

My invention contemplates the provision of any suitable means for passing paper articles successively through a bathof paraflin and by means of which the positions of the articles are.

- fin. Continuedi Hll is provided,

The carriers which I employ for the purpose of immersing the containers are sufliciently large interiorly to permit limited axial and transverse movements of any container housed therein during the coating operation. The containers will to a considerable extent oscillate within their respective housings in passing through the bath due to the surging of the paraflin bath itself, produced by the action of the carriers which are successively entering the bath upon one side and successively leaving it upon the other side of the machine. The loose retention of the containers within the carriers permits the paraffin to reach all surfaces of each container, bothv the interior and the exterior surfaces, and the slight movements which each container may have within its carrier are sufficient to insure the complete and thorough coating of all the projecting fibers, It is highly important that these fibers be coated as, in the absence of such protective -'coating upon a fiber, it will absorb moisture from the air or moisture with which it comes in direct contact and will transmit this moisture to the wall of the container, thereby softening the same and decreasing its mechanical strength. It is, of course, of equal importance that the air and moisture between the interstices of .the paper fiber of the container pelled and replaced by pregnation of the fibers themselves by paraffin is not desired, but thorough continuous coating is essential.

With containers fabricated of paper such ashave been described, it has beenfound that an immersion of s bstantially the desired effect upon the walls thereof, the air and moisture being expelled and the projecting filaments or fibers being completely coated while at the same time mechanical strength is maintained. Longer immersion oftentimes results in production of containers of decreased strength due to impregnation of the fibers. When the paper is immersed for approximately ten seconds, as aforesaid, the temperature of the paraflin is preferably maintained at approximately -175 F. It will be appreciated that with different weights and types of paper the time of immersion will vary and also that the temperature to which the paraffin has been heated will have a bearing. In any case the object will be to immerse the paper for a sufficient time to insure that its moisture and air content is expelled, the projecting fibers thereof coated, and the interstices of the paper wall filled with parafmersion after these results have been achieved is detrimental.

For the purpose of maintaining the paraflin at the desired temperature, suitable heating elements are incorporated within the housing Such a heating element is indicated generally at I00 and is seen to comprise a suitable tortuous conduit through which steam or other heated fluid may be passed. Gas heated or electrically heated elements may, of course, be substituted for that shown. Also, and for the purpose of heating the upper portion of the mechanism enclosed within the housing, a second heating unit this unit in the present instance also comprising a tortuous conduit for the circulation of steam- All parts of the conveyor, all of the carriers, and in fact all parts enclosed within the housing'are maintained at all times at a temperature above that of the melting point of paraflin so that any paraflin which is carried upwardly out of the bath upon the conveyors will ten seconds produces .contact of the container with indicated at remain liquid and fall againto the bath without congealing and thereby clogging the machine.

The time-of immersion of the containers may be varied in various ways, as by regulating, for instance, the-speed of the conveyor. Inasmuch as thecoating unit may comprise a portion of a complete automatic machine, however, it is not desirable to vary its operating speed and hence the time of immersion of the containers may be conveniently regulated by varying the depth of the paraflin bath, lowering the level of the upper surface of the bath resulting in a decreased time of immersion, and raising of surface resulting in an increased time of immersion.

As each container emerges bath it is disposed with its uppermost, permitting the coating to flow out of the interior of the container and off of its outside surfaces. The lowermost surface of the container rests on a convex surface of the Us rrier so that there is a comparatively small area of the carrier, permitting the paraffin to have maximum opportunity to escape between the lower wall of the container and the convex inner surface of the then bottomsupporting wall of the carrier. The duration of the draining of the containers may be approximately eighteen seconds, but at any rate sufficiently long to permit the flowing off of all free fiowing paraflin.

When a freshly immersed container reaches the discharge position, in which position the carrier in which it is housed occupies the position indicated at D in Figure 1, its walls are substantially free of excess paraflin, the draining operation being substantially completed. A slight further drainage occurs, however, after ejection of the container from the carrier and during inversion of the container by the mechanism previously described and which is illustrated in Figure 6. Thus, after the container has been again positioned vertically with closed end lowermost, as

C in Figure 6, there is a slight downward drainage along the vertical walls and this paramn when later solidified, stiffens, reinforces and renders entirely leakproof the bottom section of the container, where the pressure of any liquid later introduced is naturally the greatest.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

closed bottom end from the paraffin 1. The method of coating the inside and out- I side surfaces of an empty paper container having a closed end and an open end, a flat bottom and flat side walls, which comprises introducing the container bottom end foremost into a bath of molten paraflin, moving the same, while immersed, in such manner that all wall surfaces thereof are successively disposed at angles to the vertical, and removing the same from the bath bottom end foremost.

2. The method of coating the inside and outside surfaces of an empty paper container having a flat closed bottom and an open top and flat side walls, which comprises introducing the container bottom end foremost into a bath of molten paraifin while the longitudinal axis of the container is maintained at an angle to the vertical, moving the container, while immersed in such manner that all wall surfaces thereof are successively disposed at angles to the vertical, and removing the same from the bath bottom end foremost.

3. The method set forth in claim 2 in which container, while immersed in a bath of molten coating material so as 4. The method of coating the inner and outer surfaces of an empty paper container the walls HENRY T. SCOTT. of which are fiat, WhlCh comprises, moving the 

